U.S. patent number 6,036,167 [Application Number 09/139,949] was granted by the patent office on 2000-03-14 for solenoid-actuated control valve with mechanically coupled armature and spool valve.
This patent grant is currently assigned to Fasco Controls Corp.. Invention is credited to Richard A. Wade.
United States Patent |
6,036,167 |
Wade |
March 14, 2000 |
Solenoid-actuated control valve with mechanically coupled armature
and spool valve
Abstract
Solenoid-actuated control valves having low hysteresis include
an annular flux housing with an axial bore extending therethrough.
A coil configured to generate a magnetic field is disposed within
the flux housing. A magnetic pole piece is disposed within the flux
housing axial bore. A magnetic armature is slidably secured within
the flux housing axial bore. A spring, positioned between the pole
piece and armature, is configured to urge the armature away from
the pole piece. A spool valve, slidably secured within a spool
sleeve, is mechanically coupled with the armature such that the
spool valve follows movement of the armature as a slave.
Inventors: |
Wade; Richard A. (Shelby,
NC) |
Assignee: |
Fasco Controls Corp. (Shelby,
NC)
|
Family
ID: |
22489041 |
Appl.
No.: |
09/139,949 |
Filed: |
August 25, 1998 |
Current U.S.
Class: |
251/30.04;
123/41.12; 123/41.49; 251/38; 251/44 |
Current CPC
Class: |
F01P
7/044 (20130101); F01P 11/029 (20130101); F01P
2007/146 (20130101) |
Current International
Class: |
F16K
31/36 (20060101); F16K 31/42 (20060101); F16K
31/04 (20060101); F16K 31/383 (20060101); F16K
31/12 (20060101); F16K 031/04 (); F16K 031/383 ();
F16K 031/42 () |
Field of
Search: |
;123/41.12,41.49
;251/30.03,30.04,38,44 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Walton; George L.
Attorney, Agent or Firm: Myers, Bigel, Sibley &
Sajovec
Claims
That which is claimed is:
1. A flow control apparatus, comprising:
an annular flux housing having an axial bore extending
therethrough;
a coil configured to generate a magnetic field disposed within said
flux housing;
a magnetic pole piece disposed within said flux housing axial
bore;
a magnetic armature slidably secured within said flux housing axial
bore;
biasing means positioned between said pole piece and said armature,
said biasing means configured to bias said armature away from said
pole piece;
a spool sleeve secured to said flux housing, said spool sleeve
having a supply port and an exhaust port; and
a spool valve slidably secured within said spool sleeve, said spool
valve mechanically coupled with said armature such that said spool
valve follows movement of said armature as a slave while remaining
in contact with said armature in all positions thereof, said spool
valve configured to control fluid entering said supply port and
exiting said exhaust port.
2. A flow control apparatus according to claim 1 wherein said spool
valve and said armature are mechanically coupled via a spring that
urges said spool valve into contact with said armature.
3. A flow control apparatus according to claim 1 wherein said spool
valve comprises spaced-apart first and second valve portions on
respective ends of an intermediate body portion, said first valve
portion configured to meter fluid flowing into said supply
port.
4. A flow control apparatus according to claim 3 wherein said
intermediate body portion has a smaller diameter than said first
and second valve portions and wherein said intermediate body
portion forms an annular chamber within said spool sleeve in
communication with said supply and exhaust ports.
5. A flow control apparatus according to claim 1 further comprising
means for maintaining said armature at a pressure of fluid entering
said supply port.
6. A flow control apparatus according to claim 1 further comprising
means for adjusting axial movement of said spool valve within said
spool sleeve relative to a flow of electrical current within said
coil.
7. A flow control apparatus according to claim 6 wherein said
adjusting means comprises means for axially adjusting a position of
said armature within said flux housing axial bore.
8. A flow control apparatus, comprising:
an annular flux housing having opposite first and second end
portions and an axial bore extending between said first and second
end portions;
a bobbin disposed within said flux housing, said bobbin having
conductive wire coiled therearound for generating a magnetic
field;
a magnetic pole piece disposed within said flux housing axial bore
adjacent said flux housing first end portion, said pole piece
having opposite first and second ends;
an armature chamber disposed within said flux housing axial bore
adjacent said flux housing second end portion;
a magnetic armature slidably secured within said armature chamber,
said armature including a body portion terminating at opposite
first and second ends;
first biasing means positioned within said armature chamber between
said pole piece second end and said armature first end, said first
biasing means configured to axially bias said armature first end
away from said pole piece second end;
wherein said flux housing, armature and pole piece form a magnetic
flux circuit such that flow of electrical current within said
coiled conductive wire causes said armature first end to move
axially within said armature chamber towards said pole piece second
end;
a spool sleeve comprising:
opposite first and second end portions;
a central bore terminating at said first and second end
portions;
wherein said spool sleeve first end portion is secured to said flux
housing second end portion such that said spool sleeve central bore
and said armature chamber are in fluid communication; and
a supply port adjacent said spool sleeve first end portion and an
exhaust port adjacent said spool sleeve second end portion, said
supply and exhaust ports in respective communication with said
spool sleeve central bore;
a spool valve slidably secured within said spool sleeve central
bore and having spaced-apart first and second valve portions on
respective ends of an intermediate body portion, said first valve
portion configured to control fluid flow through said supply port
and said second valve portion configured to control fluid flow
through said exhaust port;
wherein said intermediate body portion has a smaller diameter than
said first and second valve portions and forms, in combination with
said spool sleeve central bore, an annular chamber in communication
with said supply and exhaust ports; and
second biasing means positioned within said spool sleeve central
bore between said first valve portion and said spool sleeve second
end portion, said second biasing means configured to bias said
spool valve towards said armature so as to maintain contact between
said first valve portion and said armature second end such that
said spool valve follows movement of said armature as a slave while
remaining in contact with said armature in all positions
thereof.
9. A flow control apparatus according to claim 8 wherein said spool
valve further comprises a central bore extending between said first
and second valve portions, wherein said spool valve central bore is
in fluid communication with said armature chamber such that supply
fluid entering said spool sleeve second end portion can surround
said armature in said armature chamber and maintain said armature
at a pressure of said supply fluid.
10. A flow control apparatus according to claim 8 wherein said
armature body portion comprises a substantially flat, axially
extending portion.
11. A flow control apparatus according to claim 8 wherein said
armature first and second end portions each have a generally
conical configuration wherein an outside diameter of each
respective first and second end portion decreases in a direction
away from said body portion.
12. A flow control apparatus according to claim 11 wherein said
second valve portion comprises a recessed portion configured to
receive said conical armature second end portion to allow said
armature and spool valve to swivel with respect to each other.
13. A flow control apparatus according to claim 8 wherein said
armature body portion comprises an outwardly extending
circumferential bearing, and wherein said bearing is configured to
reduce contact between said armature body portion and said armature
chamber.
14. A flow control apparatus according to claim 8 wherein said
spool sleeve further comprises means for metering supply fluid
entering said spool valve, said metering means located adjacent
said supply port.
15. A flow control apparatus according to claim 14 wherein said
metering means comprises at least one aperture formed through said
spool sleeve.
16. A flow control apparatus according to claim 8 wherein said
supply port comprises at least one slot formed in said spool
sleeve.
17. A flow control apparatus according to claim 8 wherein said
exhaust port comprises a plurality of circumferentially
spaced-apart apertures formed in said spool sleeve.
18. A flow control apparatus according to claim 8 further
comprising means for adjusting axial movement of said spool valve
within said spool sleeve central bore relative to a flow of
electrical current within said coiled conductive wire, said
adjusting means located within said pole piece first end.
19. A flow control apparatus according to claim 18 wherein said
adjusting means comprises means for axially adjusting a position of
said armature within said armature chamber.
20. A flow control apparatus according to claim 8 further
comprising means for isolating said supply port from said exhaust
port, said isolating means located on said spool sleeve between
said supply and exhaust ports.
21. A flow control apparatus, comprising:
an annular flux housing having opposite first and second end
portions and an axial bore extending between said first and second
end portions;
a bobbin disposed within said flux housing, said bobbin having
conductive wire coiled therearound for generating a magnetic
field;
a magnetic pole piece disposed within said flux housing axial bore
adjacent said flux housing first end portion, said pole piece
having opposite first and second ends;
an armature chamber disposed within said flux housing axial bore
adjacent said flux housing second end portion;
a magnetic armature slidably secured within said armature chamber,
said armature including a body portion terminating at opposite
first and second ends, said armature first and second end portions
each having a generally conical configuration wherein an outside
diameter of each respective first and second end portion decreases
in a direction away from said body portion;
first biasing means positioned within said armature chamber between
said pole piece second end and said armature first end, said first
biasing means configured to axially bias said armature first end
away from said pole piece second end;
wherein said flux housing, armature and pole piece form a magnetic
flux circuit such that flow of electrical current within said
coiled conductive wire causes said armature first end to move
axially within said armature chamber towards said pole piece second
end;
a spool sleeve comprising:
opposite first and second end portions;
a central bore terminating at said first and second end
portions;
wherein said spool sleeve first end portion is secured to said flux
housing second end portion such that said spool sleeve central bore
and said armature chamber are in fluid communication; and
a supply port adjacent said spool sleeve first end portion and an
exhaust port adjacent said spool sleeve second end portion, said
supply and exhaust ports in respective communication with said
spool sleeve central bore;
a spool valve slidably secured within said spool sleeve central
bore and having spaced-apart first and second valve portions on
respective ends of an intermediate body portion, said first valve
portion configured to control fluid flow through said supply port
and said second valve portion configured to control fluid flow
through said exhaust port;
wherein said intermediate body portion has a smaller diameter than
said first and second valve portions and forms, in combination with
said spool sleeve central bore, an annular chamber in communication
with said supply and exhaust ports;
second biasing means positioned within said spool sleeve central
bore between said first valve portion and said spool sleeve second
end portion, said second biasing means configured to bias said
spool valve towards said armature so as to maintain contact between
said first valve portion and said armature second end such that
said spool valve follows movement of said armature as a slave while
remaining in contact with said armature in all positions thereof;
and
means for adjusting axial Movement of said spool valve within said
spool sleeve central bore relative to a flow of electrical current
within said coiled conductive wire, said adjusting means located
within said pole piece first end.
22. A flow control apparatus according to claim 21 wherein said
spool valve further comprises a central bore extending between said
first and second valve portions, wherein said spool valve central
bore is in fluid communication with said armature chamber such that
supply fluid entering said spool sleeve second end portion can
surround said armature in said armature chamber and maintain said
armature at a pressure of said supply fluid.
23. A flow control apparatus according to claim 21 wherein said
armature body portion comprises a substantially flat, axially
extending portion.
24. A flow control apparatus according to claim 21 wherein said
armature body portion comprises an outwardly extending
circumferential bearing, and wherein said bearing is configured to
reduce contact between said armature body portion and said armature
chamber.
25. A flow control apparatus according to claim 21 wherein said
spool sleeve further comprises means for metering supply fluid
entering said spool valve, said metering means located adjacent
said supply port.
26. A flow control apparatus according to claim 25 wherein said
metering means comprises at least one aperture formed through said
spool sleeve.
27. A flow control apparatus according to claim 21 wherein said
supply port comprises at least one slot formed in said spool
sleeve.
28. A flow control apparatus according to claim 21 wherein said
exhaust port comprises a plurality of circumferentially
spaced-apart apertures formed in said spool sleeve.
29. A flow control apparatus according to claim 21 wherein said
adjusting means comprises means for axially adjusting a position of
said armature within said armature chamber.
30. A flow control apparatus according to claim 21 wherein said
second valve portion comprises a recessed portion configured to
receive said conical armature second end portion to allow said
armature and spool valve to swivel with respect to each other.
31. A hydraulic system, comprising:
a reservoir of fluid;
a hydraulic motor having an inlet port; menas for supplying fluid
from said reservoir to said hydraulic motor inlet port; and
a flow control apparatus that controls flow of said fluid from said
fluid supplying means to said hydraulic motor inlet port, said flow
control apparatus comprising:
an annular flux housing having an axial bore extending
therethrough;
a coil configured to generate a magnetic field disposed within said
flux housing;
a magnetic pole piece disposed within said flux housing axial
bore;
biasing means positioned between said pole piece and said armature,
said biasing means configured to bias said armature away from said
pole piece;
a spool sleeve secured to said flux housing, said spool sleeve
having a supply port and an exhaust port; and
a spool valve slidably secured within said spool sleeve, said spool
valve mechanically coupled with said armature such that said spool
valve follows movement of said armature as a slave while remaining
in contact with said armature in all positions thereof, said spool
valve configured to control fluid entering said supply port and
exiting from said exhaust port.
32. A flow control apparatus according to claim 31 wherein said
spool valve and said armature are mechanically coupled via a spring
that urges said spool valve into contact with said armature.
33. A flow control apparatus according to claim 31 wherein said
spool valve comprises spaced-apart first and second valve portions
on respective ends of an intermediate body portion, said first
valve portion configured to meter fluid flowing into said supply
port.
34. A flow control apparatus according to claim 33 wherein said
intermediate body portion has a smaller diameter than said first
and second valve portions and wherein said intermediate body
portion forms an annular chamber within said spool sleeve in
communication with said supply and exhaust ports.
35. A flow control apparatus according to claim 31 further
comprising means for maintaining said armature at a pressure of
fluid entering said supply port.
36. A flow control apparatus according to claim 31 further
comprising means for adjusting axial movement of said spool valve
within said spool sleeve relative to a flow of electrical current
within said coil.
37. A flow control apparatus according to claim 36 wherein said
adjusting means comprises means for axially adjusting a position of
said armature within said flux housing axial bore.
Description
FIELD OF THE INVENTION
The present invention relates generally to control valves and, more
particularly, to solenoid-actuated control valves.
BACKGROUND OF THE INVENTION
Heat is conventionally removed from the coolant of an internal
combustion engine by passing the coolant through a radiator. One or
more cooling fans are conventionally utilized to draw air across
the radiator to facilitate heat removal from the coolant flowing
therewithin. Cooling fans may be driven directly from an internal
combustion engine or may be independently driven via a separate
power source.
Cooling fans directly driven by an internal combustion engine have
several disadvantages compared with cooling fans driven via
separate power sources. One disadvantage is that fan speeds may be
inadequate at some engine speeds which may result in inadequate or
inefficient heat removal. For example, at low engine speeds, a
cooling fan directly driven by an internal combustion engine may
not have sufficient speed to adequately draw air through a
radiator. Accordingly, at low engine speeds, the ability to
adequately remove heat from engine coolant may be reduced. At high
engine speeds, a cooling fan directly driven by an engine may have
excessive speed, thereby drawing excessive air through a radiator.
This may result in overcooling.
Furthermore, when a cooling fan is driven directly from an internal
combustion engine, mechanical devices, such as belts, splined
shafts, chains, and the like may be necessary to transfer power
from the engine to the cooling fan. These mechanical devices may
increase the complexity and expense of an internal combustion
engine and may decrease the efficiency thereof.
Cooling fans driven by an electrical motor are conventionally
configured to cycle on and off at predetermined coolant
temperatures. Unfortunately, electrical motors serving in this
capacity may have various disadvantages. One disadvantage is that
an electrical motor of sufficient power to drive one or more
cooling fans may place a strain on a vehicle's electrical system.
Also, the physical size of some electrical fan motors may be
somewhat large and, as a result, undesirable for automotive use. In
addition, electrical motors for driving cooling fans may be
somewhat noisy. Unfortunately, efforts to reduce electrical motor
noise may add to manufacturing costs and may decrease electrical
motor efficiency.
Cooling fans may also be driven by hydraulic motors. The rotational
speed of a cooling fan driven by a hydraulic motor is
conventionally controlled by varying the rate of flow of a working
fluid being pumped to the hydraulic motor that drives the cooling
fan. Typically, the rotational speed of a hydraulic motor is
increased as coolant temperature increases. Conversely, the
rotational speed of a hydraulic motor is decreased as coolant
temperature decreases.
The rate of flow of fluid to a hydraulic motor may be controlled
via a solenoid-actuated control valve. Unfortunately, conventional
solenoid-actuated control valves have various limitations. For
large internal combustion engines, multiple cooling fans may be
required. As a result, fluid flow requirements may be rather high.
For example, a pair of hydraulic motors for driving cooling fans
may jointly require between 15 and 20 gallons per minute (GPM) of
hydraulic fluid to adequately rotate the cooling fans.
Unfortunately, conventional solenoid-actuated control valves may
not be able to sufficiently handle flow rates of this magnitude.
This is because flow forces imposed on the internal components of a
control valve at high flow rates are often quite large and unstable
(non-linear). Unstable flow forces may result in unsatisfactory
performance by a hydraulic motor. In addition, the design of many
conventional solenoid-actuated control valves may lead to an
increase in valve hysteresis at large flow rates.
SUMMARY OF THE INVENTION
In view of the above discussion, it is an object of the present
invention to facilitate the use of hydraulic motors for driving
cooling fans for use with internal combustion engines.
It is another object of the present invention to provide
solenoid-actuated control valves with reduced hysteresis,
especially at high flow rates.
It is another object of the present invention to provide
solenoid-actuated control valves that can operate at high flow
rates while maintaining stable flow.
These and other objects of the present invention are provided by a
low hysteresis solenoid-actuated control valve having a spool valve
mechanically coupled with an armature of the solenoid so as to
follow the armature as a slave. An annular flux housing having an
axial bore extending therethrough houses a coil configured to
generate a magnetic field. A magnetic pole piece is disposed within
the flux housing axial bore and a magnetic armature is slidably
secured within the flux housing axial bore. A spring is positioned
between the pole piece and the armature and is configured to urge
the armature away from the pole piece. A spool sleeve is secured to
the flux housing and includes a supply port and an exhaust port. A
spool valve is slidably secured within the spool sleeve and is
mechanically coupled with the armature such that the spool valve
follows movement of the armature as a slave.
According to a preferred embodiment, an annular flux housing
includes opposite first and second end portions and an axial bore
extending between the first and second end portions. A bobbin is
disposed within the flux housing and has conductive wire coiled
therearound for generating a magnetic field. A magnetic pole piece
is disposed within the axial bore of the flux housing adjacent the
flux housing first end portion.
An armature chamber is also disposed within the flux housing
annular bore adjacent the second end portion of the flux housing. A
magnetic armature is slidably secured within the armature chamber.
The armature includes a body portion terminating at opposite first
and second ends. The armature body portion includes a substantially
flat, axially extending portion and an outwardly-extending,
circumferential bearing. The flat, axially extending portion is
configured to allow supply fluid to flow upwardly within the
armature chamber. The circumferential bearing is configured to
reduce contact between the armature and the armature chamber,
thereby reducing friction that can cause valve hysteresis.
A spring is disposed between the pole piece and the armature and is
configured to urge the armature in an axial direction away from the
pole piece. Together, the flux housing, armature and pole piece
form a magnetic flux circuit such that flow of electrical current
within the coiled conductive wire creates a magnetic field which
causes the armature to move axially within the armature chamber
towards the pole piece.
A spool sleeve, having a central bore therethrough, has a free end
and an opposite end secured to the flux housing second end portion
such that the central bore and armature chamber are in fluid
communication with each other. The spool sleeve includes a supply
port adjacent the free end and an exhaust port adjacent the end
secured to the flux housing. The supply and exhaust ports are in
respective fluid communication with the central bore of the spool
sleeve.
A spool valve is slidably secured within the spool sleeve central
bore and has spaced-apart first and second valve portions joined
together by an intermediate body portion. The first valve portion
is configured to meter fluid flow through the supply port. The
second valve portion is configured to control fluid flow through
the exhaust port. The intermediate body is portion of the spool
valve has a smaller diameter than the first and second valve
portions and forms, in combination with the spool sleeve central
bore, an annular chamber in communication with the supply and
exhaust ports. The shape of the spool valve helps produce linear
flow forces between the supply and exhaust ports, especially at
high flow rates.
The spool valve also includes a central bore that extends between
the first and second valve portions and which is in fluid
communication with the armature chamber. Accordingly, supply fluid
can enter through the spool sleeve free end and flow into the
armature chamber to maintain the armature at a pressure of the
supply fluid.
A spring is positioned within the spool sleeve central bore between
the first valve portion and the spool sleeve second end portion.
The spring is configured to urge the spool valve towards the
armature so as to maintain constant contact between the first valve
portion and the armature second end. As a result, the spool valve
follows the movement of the armature as a slave. The armature
second end and spool valve second valve portion are configured to
swivel to reduce valve hysteresis.
An adjustment screw is provided within the pole piece for adjusting
axial movement of the spool valve within the spool sleeve central
bore relative to flow of electrical current within the coiled
conductive wire. The adjusting screw adjusts the position of the
armature within the armature chamber, which thereby adjusts the
position of the spool valve coupled to the armature.
The present invention is advantageous because the configuration of
the spool valve and the physical coupling of the spool valve and
armature facilitates reducing valve hysteresis. Furthermore,
control valves incorporating a spool valve configuration according
to the present invention can achieve linear flow forces, even at
high flow rates. Solenoid-actuated control valves according to the
present invention can move or "stroke" 4 millimeters (mm) at flow
rates up to and exceeding 15 GPM. Heretofore it has been somewhat
difficult to control flow rates of this magnitude because of the
non-linear flow forces imparted on valve components at these high
flow rates. Furthermore, it has been difficult to control flow
rates up to and exceeding 15 GPM via conventional solenoid actuated
valves because of physical size limitations placed on these valves
by internal combustion engines.
Metering at the supply port, in accordance with the present
invention is particularly advantageous because fluid flow forces
remain linear, thus providing very stable performance of the
solenoid valve.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 schematically illustrates a system for controlling the
rotational speed of a hydraulically driven engine cooling fan in
which a hydraulic solenoid valve according to the present invention
may be utilized.
FIG. 2 is a perspective view of a solenoid-actuated control valve
according to an embodiment of the present invention.
FIG. 3 is an exploded perspective view of the solenoid-actuated
control valve of FIG. 2.
FIG. 4 is a cross-sectional view of the solenoid-actuated control
valve of FIG. 2 taken along lines 4--4.
FIG. 5 is a partially-fragmented side view of the solenoid-actuated
control valve of FIG. 2 illustrating actuation of the armature to
thereby meter flow at the supply port.
FIGS. 6 and 7 illustrate a spool valve for a solenoid-actuated
control valve, according to another embodiment of the present
invention.
FIGS. 8 and 9 illustrate a spool sleeve for a solenoid-actuated
control valve, according to another embodiment of the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
The present invention now will be described more fully hereinafter
with reference to the accompanying drawings, in which preferred
embodiments of the invention are shown. This invention may,
however, be embodied in many different forms and should not be
construed as limited to the embodiments set forth herein; rather,
these embodiments are provided so that this disclosure will be
thorough and complete, and will fully convey the scope of the
invention to those skilled in the art. Like numbers refer to like
elements throughout.
Hydraulic System
Referring now to FIG. 1, an exemplary system 10 in which a
solenoid-actuated control valve according to the present invention
may be utilized is schematically illustrated. The reference numeral
12 denotes an internal combustion engine, typically fitted to an
automotive vehicle, which is equipped with a radiator 14. A cooling
fan 16 is provided for pulling a stream of air across the coils of
the radiator 14, to remove heat from engine coolant flowing
therethrough, as is understood by those skilled in this art. The
cooling fan 16 is rotationally driven by a hydraulic motor 18.
Hydraulic motors are well known in this art and need not be
described herein.
The intake port 18a of the hydraulic motor 18 is connected to the
output port 22a of a hydraulic fluid pump 22 by a hydraulic conduit
20. The intake port 22b of the hydraulic fluid pump 22 is connected
to a fluid reservoir 26 by the hydraulic conduit 24 and receives a
supply of hydraulic fluid therefrom. An exemplary fluid reservoir
may be the power steering fluid reservoir of a vehicle. An outlet
port 18b of the hydraulic motor 18 is connected by another
hydraulic conduit 28 to the fluid reservoir 26 which returns spent
hydraulic fluid to the fluid reservoir 26.
The hydraulic conduit 20 incorporates a solenoid-actuated control
valve (solenoid valve) 40, as illustrated, for controlling fluid
flow to the hydraulic motor 18. The solenoid within the solenoid
valve 40 is actuated in response to electrical signals generated by
an engine coolant temperature sensor 30 that outputs an electrical
signal indicative of the temperature of the coolant of the internal
combustion engine 12. An electrical signal indicating an increase
in engine coolant temperature preferably causes the solenoid valve
to increase fluid flow to the hydraulic motor 18. Conversely, an
electrical signal indicating a decrease in engine coolant
temperature preferably causes the solenoid valve to decrease fluid
flow to the hydraulic motor 18.
Solenoid Valve
Referring now to FIG. 2, a perspective view of a solenoid valve 40,
according to an embodiment of the present invention, is
illustrated. The solenoid valve 40 includes a magnet portion 42 and
a hydraulic portion 44. The function of the magnet portion 42 is to
generate a magnetic field which operates an armature 56 (FIG. 3)
therewithin. The armature 56 is mechanically coupled with a spool
valve 46 that is slidably secured within a spool sleeve 48 and that
is configured to control the flow of hydraulic fluid
therethrough.
Referring now to FIG. 3, an exploded perspective view of the
solenoid valve of FIG. 2 is illustrated. The magnet portion 42
includes an annular flux housing 50 having opposite first and
second end portions 50a, 50b and an axial bore 51 extending between
the first and second end portions 50a, 50b. The axial bore 51
defines an axial direction indicated by reference number 53. As
will be described below with respect to FIG. 4, the annular flux
housing 50 is configured to enclose an insulating bobbin disposed
therewithin and having conductive wire wrapped therearound for
generating a magnetic field. A threaded hex washer 52 is configured
to be secured to the annular flux housing second end portion 50b,
as illustrated.
A flux return tube 76, isolation tube 78 and pole piece 68 are
secured together within the annular flux housing axial bore 51 to
form a chamber 80 within which the armature 56 can slidably move
along the axial direction 53. The flux return tube 76 is secured to
the threaded hex washer 52 as illustrated. A magnetic armature 56
and spring 58 are slidably secured within the armature chamber 80.
An adjusting screw 60 is threadingly secured within an end of the
pole piece 68.
Still referring to FIG. 3, a spool valve 46 is slidably secured
within a spool sleeve 48. As will be described in detail with
respect to FIG. 4, a spring 62 is configured to bias the spool
valve 46 towards the armature 56, so that the spool valve 46 is
mechanically coupled with the armature 56 and moves with the
armature 56 as a slave.
Referring now to FIG. 4, the magnet portion 42 and hydraulic
portion 44 of the solenoid valve 40 of FIG. 4 will now be described
in greater detail. Disposed within the annular flux housing 50 is a
bobbin 64 having conductive wire 66 coiled therearound for
generating a magnetic field when electrical current flow is induced
therein via electrical terminals 67. Magnetic coils for operating
solenoids are well understood by those skilled in this art and need
not be described further herein.
A magnetic pole piece 68 is disposed within the annular flux
housing axial bore 51 adjacent the annular flux housing first end
portion 50a, as illustrated. The pole piece 68 includes an axial
bore 70 extending along the axial direction 53 between opposite
first and second ends 68a, 68b, as illustrated. A portion of the
pole piece axial bore 70 adjacent the pole piece first end 68a is
threaded and configured to receive a correspondingly-threaded
adjusting screw 60 therein. As will be described in detail below,
the adjusting screw 60 is configured to adjust or calibrate the
position of the armature 56.
In the illustrated embodiment, the adjusting screw 60 has opposite
first and second ends 60a, 60b. A seal 74, such as an O-ring,
extends around the circumference of the adjusting screw 60 adjacent
the adjusting screw second end 60b and is configured to prevent
hydraulic fluid from escaping from the armature chamber 80 through
the pole piece axial bore 70. A spring 58 is positioned between the
adjusting screw second end 60b and the armature 56 and is
configured to bias the armature 56 along the axial direction 53
away from the pole piece second end 68b. The adjusting screw 60
serves as means for adjusting (i.e., calibrating) the axial
positions of both the armature 56 within the armature chamber 80
and the spool valve 46 within the spool sleeve central bore 82
relative to flow of electrical current within the coiled conductive
wire 66 producing a magnetic field.
In the illustrated embodiment, the pole piece first end 68a extends
outwardly along the axial direction 53 from the annular flux
housing 50. A retaining ring 72 is configured to maintain the pole
piece 68 securely within the annular flux housing axial bore 51. In
the illustrated embodiment, the pole piece second end 68b has an
inverted conical shape configured to receive a conical-shaped end
of the armature 56.
Still referring to FIG. 4, the armature 56 is slidably secured
within the armature chamber 80 as illustrated. The armature 56
includes a body portion 56c terminating at opposite first and
second ends 56a, 56b. The annular flux housing 50, armature 56,
flux return tube 76, hex washer 52 and pole piece 68 form a
magnetic flux circuit such that flow of electrical current within
the coils of conductive wire 66 produces a magnetic field that
causes the armature first end 56a to move in the axial direction 53
along the armature chamber 80 towards the pole piece second end
68b. The spring 58 biases against the armature first end 56a to
counter the magnetic force attracting the armature 56 towards the
pole piece 68.
Still referring to FIG. 4, the flux return tube 76 extends through
the threaded hex washer 52 and terminates at a central bore 55 in
the threaded end 52a of the threaded hex washer 52, as illustrated.
The central bore 55 in the threaded end 52a of the threaded hex
washer 52 is configured to receive the first end 48a of the spool
sleeve 48, as illustrated. A circumferential seal 49, such as an
O-ring, extends around the first end 48a of the spool sleeve 48 as
illustrated for preventing hydraulic fluid from leaking between the
spool sleeve 48 and the inner surface 57 of the central bore 55. A
valve sleeve retaining ring 59 also extends around the first end
48a of the spool sleeve 48, as illustrated, for maintaining the
spool sleeve first end 48a securely within the central bore 55, as
illustrated.
The spool sleeve 48 has a central bore 82 extending therethrough
between opposite first and second end portions 48a, 48b, as
illustrated. The spool sleeve first end portion 48a is secured
within the central bore 55 of the threaded hex washer threaded end
52a as described above. Effectively, the spool sleeve first end
portion 48a is secured to the flux housing second end portion 50b
such that the spool sleeve central bore 82 and the armature chamber
80 within the flux housing axial bore 51 are in fluid communication
with each other.
A supply port 84 is formed within the spool sleeve second end 48b,
as illustrated. An exhaust port 86 is formed within the spool
sleeve first end 48a, as illustrated. Both the supply port 84 and
exhaust port 86 are in respective fluid communication with the
spool sleeve central bore 82. In the illustrated embodiment, the
supply port 84 includes two opposing slots 84a, 84b formed in the
spool sleeve 48. Similarly, the exhaust port includes two opposing
slots 86a, 86b formed in the spool sleeve 48. It is to be
understood that the supply and exhaust ports 84, 86 may have
various configurations, and are not limited to the illustrated
embodiment. For example, a plurality of apertures may be utilized
in lieu of slots for either or both of the supply and exhaust ports
84, 86.
In the illustrated embodiment, the spool valve 46 has a general
hour-glass shape and is slidably secured within the spool sleeve
central bore 82. The hour-glass shape of the spool valve 46 helps
produce linear flow forces resulting from hydraulic fluid entering
the supply port 84 and exiting through the exhaust port 86 at high
flow rates. The spool valve 46 has spaced-apart first and second
valve portions 46a, 46b joined together by an intermediate body
portion 46c. A central bore 47 extends through the spool valve 46
between the first and second valve portions 46a, 46b along the
axial direction 53.
The spool valve second valve portion 46b includes a recessed
portion 95 configured to receive the armature second end 56b and to
allow the armature 56 and spool valve 46 to swivel with respect to
each other. One or more notches 45 are preferably provided at the
second valve portion 46b adjacent the central bore 47, as
illustrated, to facilitate the flow of fluid around the armature
second end 56b and upwardly into the spool valve armature chamber
80. The first and second spool valve portions 46a, 46b each include
a plurality of pressure equalization grooves 54, as illustrated.
Spool valve pressure equalization grooves are well known in this
art and need not be described further herein.
The intermediate body portion 46c has a smaller diameter than the
first and second valve portions 46a, 46b and forms, in combination
with the spool sleeve central bore 82, an annular chamber 88 in
fluid communication with the supply and exhaust ports 84, 86. The
first valve portion 46a is configured to control fluid flow through
the supply port 84 and the second valve portion 46b is configured
to control fluid flow through the exhaust port 86. The spool sleeve
48 further comprises a plurality of metering apertures 98, as
illustrated, which serve as means for metering supply fluid at the
supply port 84.
The spool sleeve second end 48b includes an end cap 90 having an
aperture 92 formed through a central portion thereof, as
illustrated in FIG. 4. A spring 62 is positioned within the spool
sleeve central bore 82 between the second valve portion 46b and the
spool sleeve second end portion 48b. The spool valve first end
portion 46a includes a cavity 94 along the axial direction thereof
that is configured to receive an end of the spring 62, as
illustrated. The spring 62 is configured to bias the spool valve 46
towards the armature 56 so as to maintain constant mechanical
coupling between the first valve portion 46a and the armature
second end 56b. Accordingly, the spool valve 46 can follow the
movement of the armature 56 as a slave.
Fluid from a supply reservoir enters the supply port 84, flows
through the annular chamber 88 and exits via the exhaust port 86,
as indicated by the arrows 97 in FIG. 4. Preferably, when the
solenoid valve 40 is in an installed configuration, the supply port
84 is isolated from the exhaust port 86 via a seal 100, such as an
O-ring, extending circumferentially around an intermediate portion
48c of the spool sleeve, as illustrated. The threaded hex washer 52
is configured to be threadingly engaged within a correspondingly
threaded bore. A seal 61, such as an O-ring, circumferentially
extends around the threaded end 52a to provide a seal against
exhaust pressure.
In the illustrated embodiment, the armature first and second end
portions 56a, 56b each have a generally conical configuration,
wherein the outside diameter of each respective first and second
end portion 56a, 56b decreases along the axial direction 53 away
from the armature body portion 56c. The armature body portion 56c
also includes a substantially flat, axially extending portion 56d.
The armature body portion 56c also includes an outwardly extending
circumferential bearing 56e that is configured to reduce contact
between the armature body portion 56c and the inner surface 96 of
the armature chamber 80. The circumferential bearing 56e allows the
armature 56 to compensate for misalignment between the pole piece
68 and the spool sleeve 48 thereby reducing valve hysteresis.
In the illustrated embodiment, the spool valve second end portion
46b includes a cavity 95 along the axial direction thereof that is
configured to receive the armature second end 56b. The cavity 95
includes a step or ledge 97, as illustrated. A stop 98 extending
around a portion of the armature second end 56b is configured to
prevent the armature second end 56b from extending into the spool
valve cavity 95 beyond a predetermined amount. The conical
configuration of the armature second end 56b within the cavity 95
of the spool valve second end 46b provides a pivotable joint that
helps reduce valve hysteresis.
The armature 56 is pressure balanced because supply fluid is
allowed to enter through the end cap aperture 92, flow upwardly
through the spool valve central bore 47 and into the armature
chamber 80. The flat portion 56d of the armature body portion 56c
facilitates the flow of supply fluid into the armature chamber 80.
Accordingly, the armature 56 is maintained at the same pressure as
the supply fluid.
Solenoid Valve Operation
Referring to FIGS. 4 and 5, operation of the illustrated solenoid
valve 40 will now be described. In the absence of a magnetic field,
the armature 56 is biased axially downward away from the pole piece
68, via spring 58, as indicated by arrow 110. As a result, the
armature second end 56b pushes the spool valve second end 46b
axially downward as indicated by arrow 112, thereby causing the
spool valve first end 46a to move downwardly against the spring 62
to open the supply port 84.
When electrical current is applied to the coiled conductive wire
66, via terminals 67, a magnetic field is generated such that the
pole piece 68 magnetically attracts the armature first end 56a,
causing the armature 56 to move axially upwards towards the pole
piece 68. Because the spring 62 causes the spool valve 46 to follow
the armature as a slave, the spool valve 46 moves axially upwards,
thereby causing the spool valve first end 46a to move upwardly to
close the supply port 84. According to an embodiment of the present
invention, when electrical current is applied to the coiled
conductive wires 66, the armature 56 and spool valve 46 move to a
position where the sum of the fluid flow forces on them equals
zero.
As would be understood by those skilled in the art of solenoid
valves, upward movement of the armature 56 may be controlled by
controlling the amount of electrical current applied to the coiled
conductive wire via the terminals 67. Accordingly, in the
illustrated embodiment of FIGS. 4 and 5, the spool valve 46 meters
fluid flow at the supply port 84. Metering at the supply port 84,
in accordance with the present invention is particularly
advantageous because fluid flow forces remain linear, thus
providing very stable performance of the solenoid valve 40.
As illustrated in FIG. 5, electrical current has been applied to
the terminals 67, thereby causing a magnetic field to be generated
which causes the armature 56 to move axially upwards as indicated
by arrow 114. As a result, the spool valve 46 follows the armature
56 axially upwards as indicated by arrow 116. The spool valve first
end 46a has moved axially upwards so as to close the supply port
84, as illustrated. However, in the illustrated embodiment, the
metering apertures 98 remain partially open, thereby permitting
hydraulic fluid to flow from the supply reservoir through the spool
sleeve central bore 82 and out the exhaust port 86. The illustrated
spool sleeve 48 and spool valve 46 are configured to provide
hydraulic fluid flow of between about 0.01 GPM and about 25 GPM
with a pressure drop across the spool sleeve 48 of between 0 and
about 100 pounds per square inch (psi), depending on the flow
rate.
Alternative Spool Valve and Spool Sleeve Embodiment
Referring now to FIGS. 6-9, a spool valve 146 and spool sleeve 148,
according to another embodiment of the present invention, are
illustrated. The illustrated spool valve 146 has a generally
hour-glass shape and is configured to be slidably secured within
the central bore 182 of spool sleeve 148. The spool valve 146 has
spaced apart first and second valve portions 146a, 146b joined
together by an intermediate body portion 146c, and a central bore
147 extending therethrough along the axial direction 153. The axial
length L.sub.1 of the first valve portion 146a is less than the
axial length L.sub.2 of the second valve portion 146b, as
illustrated. One or more notches 145 are preferably provided at the
second valve portion 146b adjacent the central bore 147, as
illustrated, to facilitate the flow of fluid around an armature and
upwardly into the spool valve armature chamber, as described above.
In addition, both the first and second valve portions 146a, 146b
have respective pressure equalization grooves 154.
The spool sleeve 148, illustrated in FIGS. 8 and 9 is similar to
the spool sleeve 48 described above and illustrated in FIGS. 3 and
4 with the exception that the exhaust port 184 includes a plurality
of apertures 186 instead of slots. Used within the spool sleeve 148
of FIGS. 8 and 9, the spool valve 146 is configured to meter
hydraulic fluid flow at the exhaust apertures 186, instead of at
the supply port 184.
The foregoing is illustrative of the present invention and is not
to be construed as limiting thereof. Although a few exemplary
embodiments of this invention have been described, those skilled in
the art will readily appreciate that many modifications are
possible in the exemplary embodiments without materially departing
from the novel teachings and advantages of this invention.
Accordingly, all such modifications are intended to be included
within the scope of this invention as defined in the claims. In the
claims, means-plus-function clauses are intended to cover the
structures described herein as performing the recited function and
not only structural equivalents but also equivalent structures.
Therefore, it is to be understood that the foregoing is
illustrative of the present invention and is not to be construed as
limited to the specific embodiments disclosed, and that
modifications to the disclosed embodiments, as well as other
embodiments, are intended to be included within the scope of the
appended claims. The invention is defined by the following claims,
with equivalents of the claims to be included therein.
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